Those World Rugby ratings give some really useful info for gambling, much more than just who is ranked higher. World Rugby purposely created the rating system to be predictable. The rating difference is used to get the probability that the higher rated team will beat the lower-rated team, after adding three points to the home team rating. After the game, the ratings are adjusted based on the difference between the actual result and the probability going in. I looked at the last five Rugby WCs. The higher rated teams have won 86% of the non-tied matches. That’s amazing accuracy.

For the WC, add three points to Japan’s rating. Suppose the higher-rated team is d points better. According to World Rugby’s examples, the higher rated team has a probability of winning equal to 0.5 + (d/20). You have to limit that from 0.1 to 0.9.

Let’s look at the current ratings. Wales is tops with 89.43 just barely ahead of NZ with 89.40. That 0.03 advantage means that Wales is .5 + (.03/20) or .5015 likely to beat NZ, making NZ .4985 likely to win. I’d say that’s’ a toss-up. Now, if number 1 Wales (89.43) plays number 3 Ireland (88.69) that 0.74 rating difference means that Wales in .5 + (.74/20) or .537 likely to win. The fair decimal odds would be 1/.537 or 1.86, so you could bet on Wales if is you can find a price of more than 1.86.

When we get closer to the WC, I’ll take the last pre-WC Rugby World ratings and give you the probability of the match-ups in the group phase. We’ll see what that looks like.

Cheers,

Ray Stefani